Investigations on vertebrate motor control will be concerned with the vestibulo-cerebellum, vestibulospinal system, vestibular efferents and motion sickness. Studies on the vestibulocerebellum will emphasize the integration of inputs from different areas of the labyrinth, the eye and the neck. Experiments will utilize field potential and single-cell recording. Experiments on the vestibulospinal system will be concerned with the actions of individual vestibular neurons on spinal motoneurons. One approach will be to study the intracellular potentials evoked in the target cell when extracellular activity of the first cell is used to trigger an averager. This method will be used to study the location of excitatory and inhibitory vestibular nucleus neurons, and branching of vestibular neurons acting on neck motoneurons. In a different experiment, we will also investigate the actions of the sacculus on neck motoneurons. In studying the vestibular efferent system we will use stimulation in the labyrinth to study the branching of efferent axons and inputs to efferent cells. Such data should help us understand the function of the efferent system. Finally, we will use field potential and single-unit recording to study the labyrinthine input to several loci in the CNS believed implicated in the production of motion sickness. Our objective is to gain insight into the neural events leading to motion sickness symptoms, and hopefully to develop a system favorable for testing anti-motion sickness drugs.